Paper pick-up module

Abstract

A paper pick-up module. The paper pick-up module comprises a pick plate for loading paper, a pick-up roller disposed above the pick plate to contact and convey the paper, a first elastic member biasing the pick plate upward, a first cam rotatably disposed above the pick plate and contacting the pick plate to make the paper separated from the pick-up roller, a second cam disposed above the pick plate, contacting the pick plate and rotated with the first cam, and a second elastic member biasing the second cam. When the first cam is separated from the pick plate, the pick plate moves upward and contacts the second cam due to the biasing force of the first elastic member, and the rising speed of the pick plate is retarded by the biasing force of the second elastic member.

Description

BACKGROUND

The invention relates to a paper pick-up module for a printer, and in particular to a low-noise paper pick-up module for a printer.

A conventional paper pick-up module for a printer is disclosed in U.S. Pat. No. 6,293,537. FIGS. 1 and 2 depict the motion of the described paper pick-up module. A pick plate 116 is used to load paper. A pick-up roller 111 and a cam 112b rotate with respect to an axis 112a. When the pick-up roller 111 conveys the paper to the left-hand side of the figure, the cam 112b contacts and pushes a block 115 disposed on the pick plate 116, whereby the pick plate 116 is pushed down to separate the paper from the pick-up roller 111. A spring 117 disposed under the block 115 biases the block 115. When the cam 112b is released from the block 115, the pick plate 116 is moved upward by the spring 117 to contact the pick-up roller 111 again.

The spring 117, however, has considerable spring force. When the cam 112b is released from the block 115, the pick plate 116 moves upward quickly impacting the pick-up roller 111 due to the spring force of the spring 117. This results in a loud noise and may damage the pick-up roller 111.

SUMMARY

An exemplary embodiment of a paper pick-up module of the invention comprises: a pick plate loading paper; a pick-up roller disposed above the pick plate to contact and convey the paper; a first elastic member biasing the pick plate upward enabling the paper to contact the pick-up roller; a first cam rotatably disposed above the pick plate and moving the pick plate up and down by contacting with and separating from the pick plate to enable the pick-up roller to separate and contact the paper; a second cam rotatably disposed above the pick plate and rotated by the first cam; and a second elastic member biasing the second cam. When the first cam rotates to separate from the pick plate, the pick plate moves upward to contact the second cam due to the bias force of the first elastic member, and rising speed of the pick plate is slowed down by the second elastic member biasing the second cam.

The first cam and the second cam can rotate with respect to the same axis. Furthermore, the pick-up roller, the first cam and the second cam can rotate with respect to the same axis. The second cam can be adjacent to the first cam.

The paper pick-up module further comprises a coupling element disposed on the first cam. When the first cam rotates, the coupling element contacts and rotates the second cam.

The pick plate comprises a first groove with which the first cam contacts to move the pick plate up and down. The pick plate further comprises a second groove contacting the second cam. The second groove can be longer than the first groove.

The pick plate can comprise a slot. When the first cam enters the slot, the pick plate contacts the second cam.

The first elastic member can be a compression spring. The second elastic member can be a torsion spring.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:

FIGS. 1 and 2 are schematic views of a conventional paper pick-up module for a printer;

FIG. 3 is a schematic view of a preferred embodiment of a paper pick-up module of the invention;

FIGS. 4 a, 4 b and 4c depict the position of the first cam and the second cam;

FIGS. 5 to 9 depict the motion of the paper pick-up module of the invention;

FIG. 10 is a perspective view of a pick plate of the invention; and

FIGS. 11 a to 11d are perspective views of another preferred embodiment of the invention.

DETAILED DESCRIPTION

Referring to FIG. 3, a paper pick-up module 100 comprises a pick plate 10, a pick-up roller 20, a first cam 30, a second cam 40, a first elastic member 50, a first groove 60 and a second groove 70. The pick plate 10 is used to load paper 7. The pick-up roller 20 is disposed above the pick plate 10 and can contact the paper 7. A driver 8 rotates the pick-up roller 20 via a shaft 5. Both the first cam 30 and the second cam 40 are disposed above the pick plate 10, and the second cam 40 is adjacent to the first cam 30. Because the first cam 30 is driven by the shaft 5 and the second cam 40 is pivoted to the shaft 5, the second cam 40 can be moved by the first cam 30 to rotate with respect to the shaft 5. The first groove 60 and the second groove 70 are formed on the pick plate 10 and correspond to the first cam 30 and the second cam 40, and the groove 70 may be longer than the first groove 60. In this embodiment, the first elastic member 50 is a compression spring which is disposed under the pick plate 10 and biases the pick plate 10 upward, whereby the paper 7 on the pick plate 10 contacts the pick-up roller 20.

Referring to FIGS. 4a, 4b and 4c, a second elastic member 80 is disposed between the first cam 30 and the second cam 40. A coupling element 35 is disposed on the first cam 30. When the first cam 30 rotates with respect to the shaft 5, the coupling element 35 pushes and rotates the second cam 40 around the shaft 5. In this embodiment, the second elastic member 80 is a torsion spring as shown in FIGS. 4b and 4c. One end of the torsion spring is fixed to the first cam 30 and the other end is joined with the second cam 40. As the first cam 30 is driven by the shaft 5, no relative rotation between the first cam 30 and the shaft 5 occurs. One end of the second elastic member 80 fixed to the first cam 30 has the same effect of that fixed to the shaft 5.

Referring to FIGS. 5 to 9, the driver 8 drives the pick-up roller 20 to rotate clockwise and convey paper 7, and the first cam 30 and the second cam 40 also rotate clockwise as shown in FIG. 5. When the first cam 30 contacts the first groove 60, the first cam 30 pushes the pick plate 10 downward against the biasing force of the first elastic member 50 to separate the paper 7 from the pick-up roller 20 as shown in FIG. 6. When the pick plate 10 is pushed down to the lower dead point, the first cam 30 escapes from the first groove 60. At this time, the pick plate 10 rises due to the biasing force of the first elastic member 50. The second groove 70 of the pick plate 10 pushes and rotates the second cam 40 clockwise when the pick plate 10 rises. The rising speed of the pick plate 10 is retarded due to the biasing force of the second elastic member 80 exerted on the second cam 40 as shown in FIG. 7. In such a condition, there are two methods for the second cam 40 to retard the rising speed of the pick plate 10.

The first method stops the first cam 30 for a predetermined period of certain time until the pick plate 10 rises. The second method is to rotate the first cam 30 at a very low speed relative to the rising pick plate 10.

When the paper 7 on the pick plate 10 contacts the pick-up roller 20 again, the first cam 30 drives the second cam 40 via the coupling element 35 clockwise continuously as shown in FIGS. 8 and 9.

FIG. 10 depicts a preferred embodiment of the pick plate 10. The first and second grooves 60 and 70 are formed on one side of the pick plate 10.

FIGS. 11 a to 11d depict another embodiment of the paper pick-up module of the invention. In this embodiment, the positions of the first cam 30 and the second cam 40 are different from that in the previous embodiment. The first cam 30 is disposed on the inner side, and the second cam 40 is on the outer side. Because the first cam 30 is on the inner side, a notch 12 is formed on the lateral wall of the pick plate 10 to provide the space for the rotation of the first cam 30. A flange 18 extends from the edge of the pick plate 10. In this embodiment, a slot 90 is formed in the notch 12 and on the flange 18. The first cam 30 rotates to push the pick plate 10 downward. When the first cam 30 rotates over a critical point at which the pick plate 10 moves to the lower dead point, the first cam 30 enters the slot 90 and the pick plate 10 rises due to the first elastic member 50, whereby the flange 18 contacts the second cam 40. The second cam 80 retards the rising speed of the pick plate 10 due to the second elastic member 80.

Although a printer has been described, the paper pick-up module can also be employed in other machines such as a multi-function printer or a fax machine.

While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.

Claims

1. A paper pick-up module, comprising: a pick plate loading paper; a pick-up roller disposed above the pick plate to contact and convey the paper; a first elastic member biasing the pick plate upward enabling the paper to contact the pick-up roller; a first cam rotatably disposed above the pick plate and moving the pick plate up and down by contacting with and separating from the pick plate to enable the pick-up roller to separate and contact the paper; a second cam rotatably disposed above the pick plate and rotated by the first cam; and a second elastic member biasing the second cam, wherein when the first cam rotates to separate from the pick plate, the pick plate moves upward to contact the second cam due to the bias force of the first elastic member, and rising speed of the pick plate is slowed down by the second elastic member biasing the second cam.

2. The paper pick-up module as claimed in claim 1, wherein the first cam and the second cam rotate with respect to the same axis.

3. The paper pick-up module as claimed in claim 2, wherein the pick-up roller, the first cam and the second cam rotate with respect to the same axis.

4. The paper pick-up module as claimed in claim 1, wherein the second cam is adjacent to the first cam.

5. The paper pick-up module as claimed in claim 4 further comprising a coupling element disposed on the first cam, wherein when the first cam rotates, the coupling element contacts and rotates the second cam.

6. The paper pick-up module as claimed in claim 1, wherein the pick plate comprises a first groove with which the first cam contacts to move the pick plate up and down.

7. The paper pick-up module as claimed in claim 6, wherein the pick plate further comprises a second groove contacting the second cam.

8. The paper pick-up module as claimed in claim 7, wherein the second groove is longer than the first groove.

9. The paper pick-up module as claimed in claim 1, wherein the pick plate comprises a slot, and when the first cam enters the slot, the pick plate contacts the second cam.

10. The paper pick-up module as claimed in claim 1, wherein the first elastic member is a compression spring.

11. The paper pick-up module as claimed in claim 1, wherein the second elastic member is a torsion spring.